In recent years, in company with the developments of computers and information communication equipment to be in high performance, high functionalization and networking, the operation signal tend to be in high frequency in to achieve high speed transmission and treat large capacity of information, thus new requirements have been brought up for the material of circuit board to a developing direction of multi-layer and high wiring density. These requirements comprise: 1, a good dielectric property (i.e., low dielectric constant and low dielectric loss factor), and capable to maintain stable under a condition of broad range of temperature and frequency; 2, be capable to tolerate the environmental impact of acid & alkali, high temperature and high humidity during the PCB process without moisture absorption and swelling so as to delamination and crack; 3, adapt to the process requirement of working and installation at high temperature; 4, have a good flame retardant security.
But, among the materials used in printed circuit board, adhesives mainly consisting of epoxy resin are widely employed. The dielectric constant and dielectric loss angle tangent in ordinary epoxy based laminate (FR-4 copper clad laminate) are currently high (dielectric constant 4.4, dielectric loss angle tangent about 0.02), and the high frequency characteristic is insufficient, so the ordinary epoxy based laminate is unadaptable for the requirement of high frequency signal. The skilled in the present art have employed curing agents with low polarity such as styrene maleic anhydride copolymer (SMA) or other low polarity curing agent to modify the epoxy resin for improving its high frequency dielectric property and thermal stability, in order to make the cured epoxy resin can satisfy the operational requirement as far as possible. Additionally, in order to achieve a good flame retardant property, the skilled in the art employ brominated epoxy resin which synthetized on the basis of TBBPA (tetrabromobisphenol A) to made the circuit board achieve a good flame retardant property.
Thereinafter, further discussions are proceeded with those research productions.
BE627887 discloses an epoxy resin composition using styrene maleic anhydride copolymer (SMA, its formula as follows) as epoxy resin crosslinking agent. The drawback of this epoxy resin composition is a poor thermal stability, which cause the composition unsuitable to be applied in substrate copper clad laminate for multilayer printer-circuit board (PCB).

U.S. Pat. No. 6,509,414 uses FR-4 epoxy resin, styrene/maleic anhydride copolymer, brominated epoxy resin synthetized from tetrabromobisphenol A and tetrabromobisphenol A (TBBPA) to manufacture copper clad laminate U.S. Pat. No. 6,509,414 discloses that the FR-4 epoxy resin refers to brominated epoxy resin synthetized by tetrabromobisphenol A and bisphenol A-type epoxy resin, therefore U.S. Pat. No. 6,509,414 principally discloses the production of copper clad laminate using brominated epoxy resin synthetized by tetrabromobisphenol A. This patent employs tetrabromobisphenol A combined with styrene/maleic anhydride copolymer to form a mixed curing agent to overcome the drawback of low glass transition temperature when simply using styrene/maleic anhydride copolymer as epoxy resin curing agent. But, since there are two hydroxyl groups with very strong polarity in molecular structure of tetrabromobisphenol A, the introduction of tetrabromobisphenol A deteriorate to some extent the dielectric property of the system. In addition, because the bond energy of C—Br bond in molecular structure of tetrabromobisphenol A is low, thermal decomposition would happen from about 200° C. to release small molecule gas. Therefore, the tetrabromobisphenol A has a poor thermal stability. It may cause that the board would be liable to delaminate and crack during the followed work process of PCB laminate above 260° C., and has a risk of circuit malfunction.
U.S. Pat. No. 6,667,107 uses difunctional cyanate and its prepolymer, styrene maleic anhydride and its derivative, epoxy resin, etc., to manufacture a copper clad laminate composition with low dielectric constant and low dielectric loss factor. Said copper clad laminate composition employ cyanate resin and styrene maleic anhydride and its derivative together to improve the glass transition temperature to the epoxy resin system, and has a good high-frequency dielectric property. However, there are acid anhydride groups in molecular structure of the styrene maleic anhydride copolymer used in the system, this acid anhydride group can produce carboxyl group with poor thermal stability and moisture-heat resistance, while being used in combination with cyanate, which itself have a poor moisture-heat resistance, it can further deteriorate the moisture-heat resistance. Though the moisture-heat resistance property is improved to some extent by adding epoxy resin, the improvement is limited and cannot basically eliminate the drawback, thus in the PCB manufacturing process, the laminates are easily eroded by moisture to delaminate, which results in a very low product qualification rate.
Japanese Patent JP2012012534, China application for patent CN101967264, CN101967265, CN102443138, CN102504201 use active ester as curing agent of epoxy resin to manufacture PCB laminate having a good dielectric property.
China applications for patent CN101643571, CN101643572 utilize a solution without SMA to manufacture copper clad laminate.